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New Member

Fax over IP on satellite links


I've been asked to come up with a fax over ip solution. One of the caveats is the ip solution includes a satellite link. QoS should be fairly tightly controlled - voice traffic at the moment uses LLQ. Uncongested, the link has approx 550ms delay based on 64 byte ping packets.

The faxes are likely to be coming in on 2 BRI circuits, each channel having its own number (ie 4 separate fax numbers). The calls will not be switched by a call manager - this is quite literally a relay, and the simpler it is, the better.

I have bri vics, a 1751v, and a 2811 at my disposal at the gateway end, and a 2811 at the remote end. I also have a few ATA186 devices at my disposal.

I have several questions:

1. What methods of fax transport are there.

2. What hardware is best/most reliable/most likely to work?

2. What methods/hardware have people had the most success with?

Is T.38 the only way to go with satellite links (as colleagues have led me to believe)? And which devices support T.38?

Are the ATA186 devices suitable for faxing? FXS vics suitable?

Any special requirements for the PVDMs.

Anything else which may help me will be greatly appreciated.



New Member

Re: Fax over IP on satellite links

Convert the the fax to jpg, tiff, or pdf, and email it. :-)

New Member

Re: Fax over IP on satellite links


Check IDirect devices for possible meeting your business needs. IDirect devices are very good for Data/Voice/Broadband over satellite (VSAT) links.



Re: Fax over IP on satellite links

Yes, T.38 (store and forward fax) is your only option over satellite links. There is no way you will get cisco modem relay or T.37 fax relay to work over LFN networks.

The fax on-ramp and off-ramp functions use a TCL 2.0 script so that restricts you to newer platforms and IOS >=12.2(15)T. This works very well and if your only need is to relay faxes from FXS to FXS port on routers over a sat link then this is a very simple deployment.

Cisco's web site has very good documentation as to how this is setup. Also, the IOS voice documentation has a whole section on fax and your options for relay over an IP WAN.

To clarify, you will need fxs ports on routers that support the on and off ramp TCL 2.0 scripts at both ends of the link.

Feel free to post additional questions after you have read the documentation and tried to configure it...

New Member

Re: Fax over IP on satellite links

Is there a way to simulate the problem that comes with the satellite link in a lab environment?



Re: Fax over IP on satellite links

You don't need to simulate the satellite delay or other characteristics to test T.37 fax store and forward. The incoming fax router converts the fax pages to a tiff attachment and the router sends it to the terminating fax router using the called number. The terminating fax router converts the snmp tiff attachment back to a fax and plays it out on the destination fax machine. Doesn't matter how long it takes to send the snmp tiff attachment over the satellite link.

I set this up for a large health care provider in Alaska at 50 sites and it works perfectly. In fact, every user also has their own fax number and the router will forward incoming faxes to their email!



Re: Fax over IP on satellite links

Correction, T.37 is store and forward fax using tiff attachments and SNMP between routers but faxes at both ends...

New Member

Re: Fax over IP on satellite links


does t.37 needs a smtp server in the middle of the fax gateway? or can i send those email directly to other gateway?

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